Clouds have been closely associated with poetry and the poetic since antiquity. The Latin "nubes" meant obfuscating veil, not only of the sky by atmospheric disturbance but of meaning by poetic figuration. For early modern natural philosophers, clouds exemplified the uncertain, the conjectural, the merely probable, even, indeed, the poetic. Plato called them errant causes, Aristotle imperfect mixtures. But they also had a curious kind of situatedness: they lay "in media aeris regione," between the upper and lower aerial regions, the heavens and the earth, ideas and matter, and were therefore powerful, though unreliable, forces of mediation. In this paper, I show that a concept of poetic origination developed in early modern France that derived its principles in part from the “situating incorporeality” of clouds.